Portal:Cetaceans

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EditCetaceans
A Sperm Whale fluke
The order Cetacea includes the whales, dolphins and porpoises and comprise the mammals most fully adapted to aquatic life. It contains 81 known species organized in two suborders: Mysticeti (baleen whales) and Odontoceti (toothed whales, which includes dolphins and porpoises). The order contains several record breaking species, with the Blue Whale being the largest animal known, and the Orca being the most widely distributed animal.

Cetaceans evolved from land mammals that adapted to marine life about 50 million years ago. Over a period of a few millions of years during the Eocene, the cetaceans returned to the sea. Their body is fusiform (spindle-shaped), the forelimbs are modified into flippers, the tiny hindlimbs are vestigial and the tail has horizontal flukes. Cetaceans are nearly hairless, and are insulated by a thick layer of blubber.

Cetaceans inhabit all of the world's oceans, as well as some rivers in South America and Asia. Some species can be found across the globe.

Cetology is the branch of marine science associated with the study of cetaceans.

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Narwhals "tusking"
The Narwhal (Monodon monoceros) is an Arctic species of cetacean with a body similar to that of a Beluga whale and Irrawaddy Dolphin. It is a rare creature found south of latitude 70°N. It is one of two species of whale in the Monodontidae family (the other is the beluga whale). It is possibly also related to the Irrawaddy dolphin.

The name "Narwhal" is derived from the Old Norse word náhvalr, meaning "corpse man". This probably is a reference to the mottled white and grey colouring of the skin of the adult. It may also refer to the way a narwhal can lie belly up, motionless, for a few minutes at a time. The Narwhal is also commonly known as the moon whale.

The most conspicuous characteristic of male narwhals is their single extraordinarily long tusk, which is a tooth that projects from the left side of the upper jaw and forms a left-handed helix. The tusk can be up to 3 m (nearly 10 ft) long (compared with a body length of 4–5 m [13–16 ft]) and weigh up to 10 kg (22 lb). One in 500 males has two tusks, which occurs when the right tooth, normally small, also grows out. Rarely, a female narwhal may also produce a tusk.

The purpose of the tusk has been the subject of much debate. Early scientific theories supposed that the tusk was used to pierce the ice covering of the narwhal's Arctic Sea habitat. Others suggested the tusk was used in echolocation. More recently, scientists believed the tusk is primarily used for showmanship and for dominance: males with larger tusks are more likely to successfully attract a mate. This hypothesis was suggested by the activity of "tusking", in which two males rub their tusks together.

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2014[edit]

January[edit]

The clymene dolphin (Stenella clymene) became the first confirmed naturally occurring hybrid marine mammal species when DNA analysis showed it to be descended from the spinner dolphin and the striped dolphin. [1]

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  • 10 February - Filipino fishermen have rescued around 200 melon-headed whales which were stranded in shallow waters off the coast of Bataan. Only three dolphins were reported to have died. more

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A dead Atlantic Northern Right Whale after colliding with a ship propeller.
  • ...the leading cause of death in North Atlantic Right Whales is injury sustained from colliding with ships.
  • ...the Spade Toothed Whale is the rarest, and probably the most poorly known large mammalian species.
  • ...the ear bone in cetaceans is fused to the walls of the bone cavity where the ear bones are, making hearing in air nearly impossible. Instead sound is transmitted through their jaws and skull bones.
  • ...from its discovery by John Edward Gray in 1850 until a re-assessment in 1981, the Clymene Dolphin was regarded as sub-species of the Spinner Dolphin.
  • ...the Australian Snubfin Dolphin (Orcaella heinsohni) is a recently recognised species of dolphin first described in 2005.
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Baleen from a mysticete cetacean.
Photo credit: David Monniaux

Baleen makes up baleen plates, which are arranged in two parallel rows that look like combs of thick hair; they are attached to the upper jaws of baleen whales. It is composed of keratin, which is the same substance that makes up human hair and nails. Whales use these combs for filter feeding. Whales are the only vertebrate group to use this method of feeding in great abundance (flamingos and crabeater seals use similar methods, but do not have baleen), and it has allowed them to grow to immense sizes. The Blue Whale, the largest animal ever to live, is a baleen whale.

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Recorded in the Atlantic


Recorded by the National Park Service, using a hydrophone that is anchored near the mouth of Glacier Bay, Alaska for the purpose of monitoring ambient noise.

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Whale species

Andrews' Beaked WhaleBalaenoptera omuraiBelugaBlainville's Beaked WhaleBlue Whale Cscr-featured.svgBottlenose WhaleBowhead WhaleBryde's WhaleCuvier's Beaked WhaleDwarf Sperm WhaleFin Whale Cscr-featured.svgGervais' Beaked WhaleGiant beaked whaleGinkgo-toothed Beaked WhaleGray WhaleGray's Beaked WhaleHector's Beaked WhaleHubbs' Beaked WhaleHumpback Whale Cscr-featured.svgLayard's Beaked WhaleLongman's Beaked WhaleMelon-headed WhaleMinke WhaleNarwhalPerrin's Beaked WhalePygmy Beaked WhalePygmy Killer WhalePygmy Right WhalePygmy Sperm WhaleRight Whale Cscr-featured.svgSei Whale Cscr-featured.svgShepherd's Beaked WhaleSowerby's Beaked WhaleSpade Toothed WhaleSperm Whale Symbol support vote.svgStejneger's Beaked WhaleTrue's Beaked Whale

Dolphin species

Atlantic Spotted DolphinAtlantic White-sided DolphinAustralian Snubfin DolphinBaijiBotoChilean DolphinClymene DolphinCommerson's DolphinCommon Bottlenose DolphinDusky Dolphin Symbol support vote.svgFalse Killer WhaleFraser's DolphinGanges and Indus River DolphinHeaviside's DolphinHector's DolphinHourglass DolphinHumpback dolphinIndo-Pacific Bottlenose DolphinIrrawaddy DolphinKiller Whale Cscr-featured.svgLa Plata DolphinLong-beaked Common DolphinLong-finned pilot whalePacific White-sided DolphinPantropical Spotted DolphinPeale's DolphinPygmy Killer WhaleRight whale dolphinRisso's DolphinRough-toothed DolphinShort-beaked Common DolphinShort-finned pilot whaleSpinner DolphinStriped DolphinTucuxiWhite-beaked Dolphin

Porpoise species

Burmeister's PorpoiseDall's PorpoiseFinless PorpoiseHarbour PorpoiseSpectacled PorpoiseVaquita

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Aboriginal whalingAmbergrisAnimal echolocationArchaeocetiBaleenBaleen whaleBeached whaleBeaked WhaleBlowhole (biology)BlubberBottlenose dolphin Symbol support vote.svgCallosityCephalorhynchusCetaceaCetacean intelligenceCetologyCetology of Moby-DickCommon dolphinCumberland Sound BelugaDolphinDolphinarium Symbol support vote.svgDolphin drive hunting Symbol support vote.svgEvolution of cetaceansExploding whaleHarpoonHistory of whalingInstitute of Cetacean ResearchInternational Whaling CommissionLagenorhynchusMelon (whale)Mesoplodont WhaleMilitary dolphinMoby-DickMocha DickMonodontidaeOceanic dolphinOrcaellaPilot Whale Symbol support vote.svgPorpoiseRiver dolphinRiver Thames WhaleRorqualsSperm whale familySperm whalingSpermacetiStenellaTay WhaleThe Marine Mammal CenterToothed WhaleU.S. Navy Marine Mammal ProgramWhaleWhalingWhale and Dolphin Conservation SocietyWhale surfacing behaviourWhale oilWhale louseWhale songWhale watchingWolphin

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  1. ^ http://news.nationalgeographic.com/news/2014/01/140111-hybrid-dolphin-species-ocean-animal-science/